Serious concerns were raised by public spending watchdog Audit Scotland, who investigated last year.

But yesterday the Accounts Commission ordered the body to dig for “further evidence and clarification” on the details of the controversial arrangement.

At the time Strathclyde Fire and Rescue chiefs said they wanted him to stay on until after the 2014 Commonwealth Games and to oversee an overhaul of the fire service.

I’m not some fat cat cheating the system

Brian Sweeney last year

Last year he insisted: “I’m not some fat cat cheating the system.”

At a meeting yesterday, the commission considered a report from Fraser McKinlay, controller of audit at Audit Scotland, which highlighted concerns raised in an earlier report by PriceWaterhouse Coopers.

The report said that Mr Sweeney’s retirement and subsequent re-employment a month later allowed him to access his pension lump sum, but not his annual pension.

It means that Strathclyde Fire and Rescue Board and Mr Sweeney could each be subject to an unauthorised payment charge.

Mr McKinlay’s report told how the board “agreed to make provision to meet the potential costs of both unauthorised payment charges”, believed to amount to £206,715.

The commission has asked Mr McKinlay to carry out further work and report back.

Accounts Commission chairman John Baillie, said: “We have decided to seek further clarification from the controller of audit on the arrangements made by Strathclyde Fire and Rescue for its chief fire officer’s retirement.”

The watchdog made its move after an audit last year by PriceWaterhouseCoopers expressed concern.

However, the board said this report had “failed to provide a balanced or even accurate view in relation to the section about the chief officer’s retirement and re-employment”.

It comes just months after Strathclyde Fire and Rescue Service were slammed over the death of solicitor Alison Hume, 44.

She fell down a mine shaft and died after fire service safety rules caused a major delay in mounting a rescue.

Mr Sweeney apologised to Ms Hume’s family, offering his “deep and profound regret” following a Fatal Accident Inquiry last year.

Her family are now considering suing the service over the botched rescue at Galston, Ayrshire.